Conventional techniques for printing in black-and-white and in color include letterpress printing, rotogravure printing and offset printing. These processes produce high-quality copies, but the printing members used to transfer ink, in an “imagewise” fashion onto a recording medium, are relatively expensive. Letterpress and gravure printing members, for example, are cut or etched using cumbersome photographic masking and etching techniques. Traditional offset lithography utilizes mats or films on which the image is present as a pattern of ink-accepting and ink-rejecting areas. In wet lithography, fountain solution is applied to hydrophilic plate areas, which are thereby rendered oleophobic and reject ink; the remainder of the plate is oleophilic, i.e., capable of accepting ink. In dry lithography, non-image regions of the plate are inherently oleophobic. In either case, the inked plate, which bears the imagewise pattern of ink, is brought into contact with a relatively soft blanket cylinder. From there, the ink is applied to paper or another recording medium brought into contact with the surface of the blanket cylinder.
Although lithographic printing plates are less expensive than letterpress and rotogravure printing members, they still represent a consumable material cost, and must be stored, handled, and disposed of after completion of a printing job.